What is the term for a number that is divisible by only 1 and itself?

A prime number is defined as a natural number greater than 1 that has no positive divisors other than 1 and itself. This means that a prime number can only be evenly divided (without leaving a remainder) by the number 1 and the number itself, making it unique among natural numbers. For example, the number 5 is prime because the only numbers that can divide it evenly are 1 and 5.

In contrast, composite numbers have additional divisors, meaning they can be divided evenly by numbers other than just 1 and themselves. Even and odd numbers refer to the divisibility by 2, rather than the overall characteristics of being divisible by 1 and itself. Therefore, prime number accurately identifies the characteristic described in the question.